''We also — we also need to lift the ban on stem cell research — (cheers, applause) and find cures that will help millions of Americans. (applause continues)."

Applause continues. That's a direct quote from the transcript of the speech that Sen. Hillary Rodham Clinton gave at the Democratic convention last week. Unexpectedly, the applause continued all week long, for anyone who spoke about stem cell research. Sen. John Kerry got some for asking, "What if we have a president who believes in science, so we can unleash the wonders of discovery — like stem cell research — and treat illness for millions of lives?" Ron Reagan, son of the late president, who mistakenly imagined he was being cheered merely for what he said rather than who his father was, hit an even higher rhetorical note: "Sound like magic? Welcome to the future of medicine."

Listening to all these speeches, you might have come away with the impression that stem cell research is illegal in this country, and that if our recalcitrant, medieval, anti-science fundamentalist president would only "lift the ban," or lose the election, there would be "magic" cures for old people with Alzheimer's and children with diabetes. By coincidence, the quadriplegic actor Christopher Reeve told CNN last weekend that he would walk again "in the next three to five years" with the help of stem cell research. He spoke of the obstacles to that goal as political rather than merely medical. The message: President Bush has grounded Superman.

As it happens, I do think we should liberalize our national policy on stem cell research. But before we do that, it's important to be pretty clear about what that national policy actually is, and how it got to be that way. Stem cell research is not, in fact, either illegal or unfunded: The federal budget in 2003 included $24.8 million for human embryonic stem cell research — up from zero in 2000. Private funding of stem cell research, which is unlimited, runs into the tens and possibly hundreds of millions of dollars. The current, admittedly hairsplitting policy came about because Congress in 1995 passed a ban on federal (but not private) funding for any form of research that involved the destruction of human embryos, because it is a form of research many American voters dislike and don't want to pay for. After some important (privately funded) breakthroughs, the Clinton administration began looking for legal ways to bypass the ban, but never got around to paying for any actual research.

The Bush administration thought about it, too, and came up with a solution: Federal funding could be used for research on stem cell lines already in existence. In practice, this means scientists who get their funding from the government are restricted in which materials they can use. Although this compromise will soon become a real obstacle to research, for the moment the irritant is largely philosophical. "What hampers people is the concept that there is a lack of freedom to operate," one scientist told me.

If all of that sounds a little long-winded and complicated, that's because it is. The question now is whether we want, as a nation, to continue to have long-winded and complicated debates about complicated issues, or whether we want to resort to slogans such as "lift the ban" and "unleash the wonders of discovery." The question is also whether Americans and their political representatives are allowed to think twice about the implications of brand-new science — a prerequisite for public support, one would think — or whether the patients' groups and pollsters behind last week's rhetoric always get the last word.

At some point we also need to make some distinction between science and "magic." It is true that funneling more money into biological research will produce more breakthroughs and more cures. It is also true that even with unlimited funding, Reeve might never walk again. This is research, not abracadabra. Talk of "magic" doesn't do much to reverse widespread scientific illiteracy either, which remains a far greater obstacle to scientific progress than the president.

But simplifying the argument must work as a political tactic or the Kerry campaign wouldn't have let so many people do it. Perhaps it's because "stem cell research" makes a more attractive cultural buzzword than "abortion," and a more unifying cultural issue than gay marriage. Perhaps it's because it is so easy to use personal anecdotes — Ron Reagan spoke of a 13-year-old girl who decorates her insulin pump with rhinestones — to turn a dry scientific subject into an emotional one. Or perhaps it's because the discussion taps into an old and familiar metaphor — Galileo vs. the pope, Voltaire vs. the clerics, progress vs. religion — which helps people feel more comfortable about choosing sides. Call me antediluvian, but I'd still like it better if debates about science began with facts.